Gatlin is just being himself, it's Usian Bolt who is on the decline. I've seen more pictures of him with a tired or worried look on his face this season than all his other seasons combined. It is not coming easy for him anymore. And if he has to really work at it he will fail as we are going to be seeing soon. He'll still win the 200m in around 19.68. He'll run the 100m in 9.80 losing to Gatlin's 9.78.
The money and the good life have taken their toll.
If Gay had run he wins in 9.70.